title: Improved detection sensitivity of D-mannitol crystalline phase content using differential spectral phase shift terahertz spectroscopy measurements.
abstract: We report quantitative measurement of the relative proportion of δ- and β-D-mannitol crystalline phases inserted into polyethylene powder pellets, obtained by time-domain terahertz spectroscopy. Nine absorption bands have been identified from 0.2 THz to 2.2 THz. The best quantification of the δ-phase proportion is made using the 1.01 THz absorption band. Coherent detection allows using the spectral phase shift of the transmitted THz waveform to improve the detection sensitivity of the relative δ-phase proportion. We argue that differential phase shift measurements are less sensitive to samples' defects. Using a linear phase shift compensation for pellets of slightly different thicknesses, we were able to distinguish a 0.5% variation in δ-phase proportion.
authors.affiliation: Département de radiobiologie et médecine nucléaire, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Allard
authors.forename: Alain
authors.initials: A
authors.lastname: Cornet
authors.forename: Christophe
authors.initials: C
authors.lastname: Debacq
authors.forename: Marc
authors.initials: M
authors.lastname: Meurens
authors.forename: Daniel
authors.initials: D
authors.lastname: Houde
authors.forename: Denis
authors.initials: D
authors.lastname: Morris
mesh_terms: D000465:Algorithms; D003460:Crystallization; D008353:Mannitol / Q000032:analysis* / Q000737:chemistry*; D044367:Phase Transition; D055068:Terahertz Spectroscopy / Q000379:methods*
chemical_list: D008353:Mannitol